Powder sprayer of high-tension discharge type

ABSTRACT

A powder spray of high-tension discharge type has an elongated thin main body installed within a narrow restricted space of a printing machine or the like. The main body comprises a roller, an elongated blockaded space closed at one side by the roller, and an elongated blockaded passage communicating with the blockaded space at one end portion thereof. Powder is a powder box provided separately from the main body is fed into the blockaded space by a feed screw conveyor passing through said space. The powder carried outside of the main body in accordance with the rotation of the roller is blown-down by discharge between the roller and an insulated electric wire extending parallel to said roller. The extra powder in the space is carried into the blockaded passage and is returned to the powder box by another screw conveyor passing through the blockaded passage.

United States Patent lnventor App]. No. Filed Patented Assignee POWDER SPRAYER 0F HIGH-TENSION DISCHARGE TYPE 9-Clairns, 5 Drawing Figs.

BOSb 5/04 317/3 Field of Search References Cited UNITED STATES PATENTS 12/1963 Dunaway 12/1966 Buhler 3,457,080 7/1969 Watkins Primary ExaminerLee T. Hix Attorney-Richards & Geier ABSTRACT: A powder spray of high-tension discharge type has an elongated thin main body installed within a narrow restricted space of a printing machine or the like. The main body comprises a roller, an elongated blockaded space closed at one side by the roller, and an elongated blockaded passage communicating with the blockaded space at one end portion thereof. Powder is a powder box provided separately from the main body is fed into the blockaded space by a feed screw conveyor passing through said space. The powder carried outside of the main body in accordance with the rotation of the roller is blown-down by discharge between the roller and an insulated electric wire extending parallel to said roller. The extra powder in the space is carried into the blockaded passage and is returned to the powder box by another screw conveyor passing through the blockaded passage.

PATENTEDSEPMISH I 3504 53 1 SHEET 1 OF 3 F l G. l

44 CONTROL -cz= v BOX 80 I DRWE DRVE FOR POWDER FOI? ROLLER DELIVERY POWDER 82 GENERATING- 50X I DEVICE I r W "1 MAIN BODY 1 h 4 L 8| IO l2 INVENTOR 5. SCLL I'JO ATTORNEYj MENU-113w:4m

SHEET 2 OF 3 ATTORNEYS PATENTED SEP] 4197 SHEU 3 0F 3 3 604 9 1 IN VENTOR 5. S CLL't ATTORNEYS POWDER SPRAYER OF HIGH-TENSION DISCHARGE TYPE This invention relates to an apparatus for spraying powder upon the surface of papers and synthetic films to prevent ink offset on any printed sheet and to eliminate blocking in the processing of synthetic film or rubber sheeting and more particularly to a powder sprayer of high-tension discharge type wherein the powder attaching to the peripheral surface of a roller rotating at a fixed speed is blown down by ion-wind generated by means of corona discharge and is sprayed upon the surface of the painted sheets or the like passing below the roller.

The method for spraying powder which acts as an antioffset agent, antiblocking agent or slipping agent is generally divided into two types on the basis of energy sources for spraying, namely, the air spray type and the high-tension discharge type. The high-tension discharge type is superior to the air spray type in that the powder is blown down in a plane shape, that the spray amount is adjustable to any desirable extent, that the uniform spraying is positively performed, and that there is no bad effect on the printed sheet.

In a conventional powder sprayer of high-tension discharge type, a powder box is directly connected to the top of a main body of the powder sprayer and a discharge tube is provided in the main body. When such a powder sprayer is to be installed into a restricted space, for example, between delivery chains forming a part of a delivery apparatus of the printing machine, the height of the sprayer has occasionally prevented the sprayer from being installed therein. When the height of the sprayer is to be restricted so that it can be installed into the restricted space, the capacity of the powder box is reduced. Therefore, replacement of the powder is often required. The operation of replenishing the powder storage box with fresh powder during the delivery apparatus in motion is dangerous and difficult. In addition, in the powder sprayer employing the discharge tube, the powder blown down by means of the ionwind and then descending like mist may be piled upon the discharge tube of relatively large diameter, resulting in the dripping of powder. The maintenance expenses caused by consumption of the discharge tube have also been costly.

An object of the present invention is to eliminate the drawbacks of existing devices. 5

Another object of the present invention is to provide a powder sprayer of the high-tension discharge type wherein a main body of the sprayer is made independent from a powder box to allow a very thin structure of the main body, so that the main body may be installed into a narrow restricted space, the powder box is installed, at a desired place, apart from the main body so that the fresh powder may be supplied easily.

Yet another object is the provision of a powder delivery device connecting the main body with the powder box which is simple in construction and easy to operate and is able to supply the powder homogeneously along the lengthwise direction of the main body irrespective of any length thereof, and wherein the dripping of the powder is eliminated.

Other objects of the present invention will become apparent in the course of the following specification.

The invention will appear more clearly from the following detailed description when taken in conjunction with the accompanying drawings, showing by way of example only, preferred embodiments of the inventive idea.

In the drawings:

FIG. I is a diagram showing an arrangement of each element composing a powder sprayer of high-tension discharge type according to the present invention;

FIG. 2 is a plane view, partially in section of the powder sprayer according to this invention;

FIG. 3 is a front view of a main body of the powder sprayer;

FIG. 4 is a section along the line IV--IV of FIG. 2; and

FIG. 5 is a perspective view, partially in section of the main A powder sprayer of high-tension discharge type according to an illustrated embodiment of the present invention comprises basically an elongated thin main body 10, a powderbox 40 provided separately from the main body 10, a powder delivery device 50 connecting the main body 10 with the powder box 40, drive means 70 for the powder delivery device 50, drive means for a roller 17 mounted rotatably in the main body 10, an insulated electric wire 18 extending close to the roller 17 in the main body 10, and a high-tension generating device for supplying high-tension to the wire 18 to produce corona discharge.

The main body 10 comprises right and left side holders 11 and 12, elongated upper and lower plates 13 and 14 of aluminum alloy connecting the right and left side holders, upper and lower doctor blades 15 and 16 of thin stainless steel secured to the upper and lower plates 13 and 14, respectively, a roller 17 rotatably mounted between the right and left side holders 1 l and 12, and the insulated electric wire 18 stretched between the right and left side holders 11 and 12 parallel to but spaced from the roller 17.

The roller 17 has notches of 20 to 240 mesh formed on the peripheral surface thereof by knurling or sandblast treatment. The diameter of the roller 17 is about 2.5 centimeters, the effective length is 20 to I40 centimeters and the roller is finished by hard chrome plating.

The insulated electric wire 18 extending parallel to the roller 17 is, for example, an electric wire which can withstand up to 20,000 voltage and is about 5 millimeter in diameter. The space between the electric wire 18 and the roller 17 is about 1.5 to 1.7 millimeters.

The upper and the lower doctor blades 15 and 16 made of thin stainless steel are lightly in contact with the roller 17 at the front end portion thereof appearing to embrace the roller from the upper right, as shown in FIG. 4. These doctor blades 15 and 16 are fixed to the upper and the lower plates 13 and 14 of aluminum alloy by flush head screws 21 and 22, respectively.

A space 20 is provided between the right and the left side holders 11 and 12, the upper and the lower plates 13 and 14, the upper and the lower doctor blades 15 and I6, and the roller 17. A U-shaped blockaded passage is formed through a bore 23 made in the right side holder 12, the space 20, a eutout portion 24 provided in the lower plate 14 near the left side holder 11, an elongated hole 25 made through the lower plate 14 along the lengthwise direction thereof in communication with the cutout portion 24, and another bore 26 made in the right side holder 12. A plurality of annular metal fixtures 27 is provided in the space 20 at intervals along the centerline of the bore 23, each metal fixture 27 being fixed to the lower plate by its base portion 28.

As shown in FIG. 4, the elongated hole 25 and the metal holder 27 are located substantially in the same plane, and the insulated electric wire 18 is positioned in the opposite side of the point of contact of the lower doctor blade 16 and the roller 17 with respect to the vertical line of the roller and is spaced from the roller. Preferably, as shown in FIG. 5, a guide pipe 30 having a slit or opening 29 along its lengthwise direction is provided in the space communicating with the bore 23 and a semicircular opening 31 is formed in the left side holder 11 so that the guide pipe 30 and the semicircular opening form a portion of the U-shaped blockaded passage. The guide pipe 30 is fixed to the lower plate 14 by a plurality of metal fixtures (not shown) similar to the fixtures 27.

To prevent dust and oil from entering into the space 20, a gasket 32 is fixed between corners of the upper plate 13 and the lower plate 14. In the example shown in FIG. 4, the upper plate 13 is opened by means of hinges 33 fixed at one side thereof to the back of the lower plate 14. Reference numerals 19 and 34 indicate a flush head screw and dust protector, respectively.

In another example shown in FIG. 5, a case cover 35 is placed over the upper plate 13.

The powder box 40 comprises a powder storage chamber 42 closed by a cover 41, a compartment 43 containing motors and the like, and, in the example shown in FIG. 2, a control box 44. The control box 44 comprises gauges for adjusting the number of revolutions of the roller 17 to determine the amount of the sprayed powder and for adjusting the output voltage fed to the elastic wire 18 through a transformer 91, switches, and, if desired, a buzzer to sound an alarm when the amount of powder in the powder storage chamber 42 is decreased to a fixed quantity.

In the powder delivery device 50, a pipe 55 is removably secured between a connector 51 fitted in a bore provided in one sidewall of the powder storage chamber 42 and a connector 53 fitted in the bore 23 provided in the right side holder 12. A pipe 56 is also secured between a connector 42 and a connector 54, similar to the pipe 55 shown in FIG. 2. Two coil wires 57 and 58 wound in a spiral at a fixed pitch are extended through the pipes 55 and 56, respectively. The coil wires 57 and 58 are removably secured at one end to connectors 61 and 62, respectively. The connectors 61 and 62 are fixed to one end of rotary shafts 59 and 60 which project inside the powder storage chamber 42 through another sidewall of the chamber. The coil wire 57 passing through the pipe 55 also passes through metal fixtures 27 in the space 20, while the coil wire 58 passing through the pipe 56 also passes through the elongated hole 25. The other end of each of the coil wires 57 and 58 in the example shown in FIG. 2, is secured to rotary projections 63 and 64 respectively, provided inside the left side holder 1 1. I

Preferably, these coil wires 57 and 58 comprise core wires 65 and 66 and coil wires 67 and 68 made of metal. The core wire is formed by dense coiling and the coil wire is wound in a spiral around the core wires at a fixed pitch, as shown in FIG. 5.

In the embodiment shown in FIG. 5, the projections 63 and 64 shown in FIG. 2 are eliminated.

The drive means 70 for the powder delivery device 50 comprise rotary shafts 59 and 60 secured by bearings 71 and 72 having pulleys 73 and 74, respectively, at the ends thereof. The pulley 73 and 74 connected by a belt 75 are driven by a motor 76.

The drive means 80 for the roller 17 comprise a reduction gear box 81 mounted at the outside of the side holder 11. An end of an output shaft in the gear box 81 is connected to the roller 17, while an end of an input shaft in the gear box 81 is connected to the motor 76 or to an end of an output shaft of a motor, which may be different from the motor 76, through an elastic shaft 83 passing through an elastic tube 82. The number of revolutions of the roller 17 is normally about 3 r.p.m.

The high-tension generating device 90 comprises a transformer 91 which can change the primary voltage of 100 volts AC to the secondary voltage 7 kv., and a cable 92 connecting the transformer 91 to the electric wire 18.

The operation of the powder sprayer of the present invention is as follows:

The elongated thin main body 10 is mounted in the restricted space above the delivery apparatus of, for example, a printing machine by suitable fixtures (not shown). The powder box 40 is mounted in the suitable place outside of the frame of the delivery apparatus but near the delivery apparatus. The pipes 55 and 56 and the elastic tube 82 are fixed as above mentioned so that the radius of curvature of each of them is usually more than 200 millimeters.

Preferred powder used for the sprayer according to invention, consists of calcium carbonate of to 7 grain size to which is added, as dispersant, formless silicic acid anhydride treated by silicone resin.

After filling the powder storage chamber 42 with this powder, the roller 17 is rotated at a fixed speed determined in accordance with the desired spray amount and, simultane ously, the insulated electric wire 18 is discharged as the hightension is fed thereto from the transformer 91.

The coil wires 57 and 58 (or 57a and 58a) act as a flexible feed screw and a flexible return screw, respectively, as the spiral direction and the rotary direction of the coil wires are determined, so that powder may be fed and returned as shown by arrows in FIG. 2. In the embodiment shown in FIG. 5 the powder in the powder storage chamber 42 is fed to the space 20 and filled through the opening 29 of the guide tube 30. When the roller 17 in contact with the powder in the space 20 is rotated in the direction shown by arrow in FIG. 4, the excess powder attached to the rotor is removed from the surface of rotor through the contact of the roller and the doctor blade 16. Only the fixed amount of the powder in the notches of the roller is carried outside of the space 20. When the powder is carried near the electric wire 18, it is blown down by ion-wind generated by high-tension discharge between the roller and the electric wire and it descends and is sprayed uniformly upon the surface of printings or the like passing through below the main body 10. Since the insulated electric wire is small in diameter, the powder descending like mist cannot pile upon the insulated electric wire, eliminating any dripping of the powder upon the surface of the printings.

The extra powder in the space 20 is moved through the guide pipe 30 toward the left side holder 11 and then passes through the cutout portion 24 and the semicircular opening 31. The powder coming into the elongated hole is returned to the powder storage chamber 42 through the bore 26 by the action of the coil wire 58a serving as return screw. By making the pitch of the coil wire 68 greater than that of the coil wire 67 and by making the number of revolutions of the coil wires 57a and 58a equal with each other, a safety powder sprayer is provided which is free from clogging since the return amount of the powder is greater than the feed amount thereof.

I claim:

1. A powder sprayer of high-tension discharge type comprising an elongated thin main body containing an elongated roller having a rough surface and upper and lower doctor blades contacting at the front end portion of said roller and embracing obliquely said roller, said roller and upper and lower doctor blades being located within said body and forming a blockaded space along the entire length of the main body, said body having a blockaded passage formed on one side thereof along the total length thereof, said blockaded space communicating with said passage;

means extending parallel to and spaced from said roller for generating corona discharge when hightension is fed thereto;

a powder box separate from said main body;

a powder delivery device connecting said powder box to said blockaded space and to said blockaded passage for feeding powder in the powder box to said blockaded space and recovering extra powder into the powder box through said blockaded passage;

drive means for said powder delivery means;

drive means for rotating said roller; and

a high-tension generating device for feeding high-tension to said means for generating corona discharge.

2. A powder sprayer of high-tension discharge type in accordance with claim 1, wherein said means for generating corona discharge comprise an insulated electric wire stretched along the main body.

3. A powder sprayer of high-tension discharge type in accordance with claim 1, wherein said powder delivery device comprises feed and return screw conveyors consisting of continuous coil wires would in spiral, said feed and return screw conveyors passing through said blockaded space and said blockaded passage by way of the powder storage chamber.

4. A powder sprayer of high-tension discharge type in accordance with claim 3, wherein said main body further comprises right and lift holders and upper and lower plates forming said blockaded space together with the roller and the upper and lower doctor blades; said blockaded passage being formed within said lower plate and communicating with said blockaded space at the portion near the left side holder of the body; an elongated guide pipe having an opening along the lengthwise direction thereof located within said blockaded s ace parallel to said roller and in the same plane as the blockaded passage; said feed screw conveyor passing through said blockaded space being located in said guide pipe.

5. A powder sprayer of high-tension discharge type in accordance with claim 2, wherein said roller is treated by knurling or sandblast.

6. A powder sprayer of high-tension discharge type in accordance with claim 3, comprising rotary projections extending from the left side holder of the main body, the tail ends of the two screw conveyors being rotatably mounted in said rotary projections.

7. A powder sprayer of high-tension discharge type in ac cordance with claim 4, wherein each of the screw conveyors comprises a core wire coiled densely and a coil wire spirally wound around the core wire.

8. A powder sprayer of high-tension discharge type in accordance with claim 4, wherein a semicircular opening is provided in said left side holder to facilitate the communication between the blockaded space and the blockaded passage for recovering the extra powder through the semicircular opening and the blockaded passage.

9. A powder sprayer of high-tension discharge type in accordance with claim 3, wherein the pitch of the return screw conveyor is greater than that of the feed screw conveyors, the speeds of revolutions of the two screw conveyors are equal to each other, and the rotary directions of the two screw conveyors are in the opposite directions to each other. 

1. A powder sprayer of high-tension discharge type comprising an elongated thin main body containing an elongated roller having a rough surface and upper and lower doctor blades contacting at the front end portion of said roller and embracing obliquely said roller, said roller and upper and lower doctor blades being located within said body and forming a blockaded space along the entire length of the main body, said body having a blockAded passage formed on one side thereof along the total length thereof, said blockaded space communicating with said passage; means extending parallel to and spaced from said roller for generating corona discharge when high-tension is fed thereto; a powder box separate from said main body; a powder delivery device connecting said powder box to said blockaded space and to said blockaded passage for feeding powder in the powder box to said blockaded space and recovering extra powder into the powder box through said blockaded passage; drive means for said powder delivery means; drive means for rotating said roller; and a high-tension generating device for feeding high-tension to said means for generating corona discharge.
 2. A powder sprayer of high-tension discharge type in accordance with claim 1, wherein said means for generating corona discharge comprise an insulated electric wire stretched along the main body.
 3. A powder sprayer of high-tension discharge type in accordance with claim 1, wherein said powder delivery device comprises feed and return screw conveyors consisting of continuous coil wires would in spiral, said feed and return screw conveyors passing through said blockaded space and said blockaded passage by way of the powder storage chamber.
 4. A powder sprayer of high-tension discharge type in accordance with claim 3, wherein said main body further comprises right and lift holders and upper and lower plates forming said blockaded space together with the roller and the upper and lower doctor blades; said blockaded passage being formed within said lower plate and communicating with said blockaded space at the portion near the left side holder of the body; an elongated guide pipe having an opening along the lengthwise direction thereof located within said blockaded space parallel to said roller and in the same plane as the blockaded passage; said feed screw conveyor passing through said blockaded space being located in said guide pipe.
 5. A powder sprayer of high-tension discharge type in accordance with claim 2, wherein said roller is treated by knurling or sandblast.
 6. A powder sprayer of high-tension discharge type in accordance with claim 3, comprising rotary projections extending from the left side holder of the main body, the tail ends of the two screw conveyors being rotatably mounted in said rotary projections.
 7. A powder sprayer of high-tension discharge type in accordance with claim 4, wherein each of the screw conveyors comprises a core wire coiled densely and a coil wire spirally wound around the core wire.
 8. A powder sprayer of high-tension discharge type in accordance with claim 4, wherein a semicircular opening is provided in said left side holder to facilitate the communication between the blockaded space and the blockaded passage for recovering the extra powder through the semicircular opening and the blockaded passage.
 9. A powder sprayer of high-tension discharge type in accordance with claim 3, wherein the pitch of the return screw conveyor is greater than that of the feed screw conveyors, the speeds of revolutions of the two screw conveyors are equal to each other, and the rotary directions of the two screw conveyors are in the opposite directions to each other. 